Introduction to Google's Go Programming Language: GoLang

By Orhan Gazi

This book teaches go programming language. Go was originally designed at Google in 2007. 
Go is a fast and lightweight programming language. It has a quicker compilation time compared to C/C++.
Go has automatic garbage collector that frees up memory when it is no longer needed.
Go is a statically typed language, that is, errors can be caught at compile time rather than at runtime.
Go was designed to write programs for networking, and cloud-based or server-side applications.
Go has cross-platform support property, it can be compiled to run on many platforms, like windows, linux, mac and raspberry pi, etc.
The book is neatly written, and includes sufficient number of examples.
Author of the book uses his years of teaching experience to serve the topics of go programming in a clean and understandable manner.

• Language: English
• Publisher: Orhan Gazi
• Release date: Oct 7, 2023
• ISBN: 9798223642688

Book preview

Preface

In this book we explain Go programming language. Go was originally designed at Google in 2007. After its introduction, Go quickly gained popularity among programming languages. It is fast and lightweight programming language. Go is simple to learn and easy to read by other developers. It has a quicker compilation time. Go has automatic garbage collector that frees up memory when it is no longer needed. This feature eliminates the need for manual memory management, and it eliminates memory leak problem that can arise from manual memory management.

Go is a statically typed language, that is, errors can be caught at compile time rather than at runtime.

Go supports parallel programming and high-performance networking and multiprocessing applications can be achieved using Go programs. Concurrency can be achieved using go-routines and channels. Go-routines can be considered as light version of threads used in C programming. Using go-routines multiple operations can be performed at the same time. This makes Go an ideal programming language for developing high-performance and scalable network applications, as well as for performing complex computational scientific works.

Go was designed to write programs for networking, and cloud-based or server-side applications. Go has cross-platform support property, it can be compiled to run on many platforms, like windows, linux, mac and raspberry pi, etc. Go is used by many well-known companies, including Google, Uber, and Dropbox.

Go is an open-source programming language, and it is often referred to as Golang because of its former domain name, golang.org. Go has some advantages over C. C language uses stack memory to store the local variables, whereas, Go uses heap memory for local variables, and this eliminates some coding problems. For instance, when a function is terminated, local variables are destroyed in C programming, and if the function returns the address of a local variable, this creates a problem in C programming, whereas in Go programming this issue is eliminated by storing the local variables in heap memory. Syntax of Go is easier than many of the programming languages. Go has automatic data type detection  feature for variables, and even pointers can be defined without specifying the pointed data type.  For instance, a variable can be defined and initialized as

v := 30.7

and a pointer pointing to this variable can be defined as

ptr := &v

and variable data type and pointed data type is determined automatically by the compiler. It is clear that pointer declaration is quite easy in Go.

In this book we teach fundamental concepts of Go language. In chapter-1, data types are explained. Basic data types for integers are int,  int8, int16, int32,  int64 and their unsigned counterparts. Go has two data types for floating point numbers and these are float32 and  float64. It is possible to define complex numbers in Go using the data types complex64  and complex128. There is only explicit type conversion available in go programming.

In chapter-2, we explain operators used in Go languages. Chapter-3 explains conditional statements. In chapter-4 functions, methods and interfaces are explained. Go functions are very powerful functions compared to the functions of other programming languages. They can return a multiple of values of different types, and due to the heap memory storage of the local variables in functions, addresses of local variables can also be returned by Go functions. Go methods are usually associated with structure data variables. Interface is a data types in Go, and this data type is a unique feature of Go language. Using interface data type and methods it is possible to write programs employing object oriented programming features.

In chapter-5 we cover structures. Accessing to the structure object elements using pointers in Go is easier in notation compared to other programming languages. Loops and arrays are covered in chapters-6 and 7. Slices are explained in chapter-8. Manipulation of arrays and slices are quite simple in Go language. Chapter-9 explains the maps in Go. Pointers are explained in details in chapter-10. Go-routines, mutex functions, channels, atomic operations which are used for concurrent program writing are covered in chapter-11. Finally, we explain file operations in chapter-12.

This book is an introductory book in Go programming. We tried to explain fundamental concepts of Go language using simple and neat examples. This book can be ready by anyone interested in computer programming and it can also be used as a text or reference book for one semester course in computer programming in colleges and universities. Finally as a last word, I dedicate this book to my younger brother İlhan Gazi who belongs to the category of good people.

Contents

Preface

Chapter-1

Data Types in Go Language

1.1 How to Write a Go Program

1.2 Go Comments

1.3 Go Variables

1.4 Formatted Print Function: Printf

1.5 Data Types in Go Programming

1.5.1 Numeric Data Types

1.5.2 Sizeof Function

1.5.3 Float Data Types

1.5.4 Formats for Print and Scan Functions

1.5.6 String Formats

1.5.7 Complex Data Types

1.5.8 Real and Imaginary Parts of a Complex Number

1.5.9 Strings

1.6 Multiple Variable Declarations

1.7 Scanf Function

1.8 Scan and Scanln Functions

1.9 Constants in Go Programming

1.10 Go Keywords

1.11 Type Conversion in Go

1.12 Global and Local Variables

Problems

Chapter-2

Operators in Go Language

2.1 Go Operators

2.1.1 Assignment Operators

2.1.2 Arithmetic Operators

2.1.3 Logical Operators

2.1.4 Bitwise Operators in Go Programming

2.1.5 Comparison Operators

Problems

Chapter-3

Conditional Statements

3.1 If Statement

3.2 If-else Statement

3.3 Conditional Ladder Structure (if else if ladder)

3.4 Multi Conditional Structures

3.5 Nested if-else Statement

3.6 Ternary Operator (?:)  in Go

3.7 Switch Statement in Go

3.7.1 The fallthrough Keyword

3.7.2 The Switch Statement with Variable Initializer

3.7.3 The Switch Statement without Switch Expression

3.7.4 Type Switches in Go

Problems

Chapter-4

Functions, Methods and Interfaces in Go Programming

4.1 Functions

4.2 Functions with Input Parameters

4.3 Go Functions with Return Values

4.4 Unused Returned Function Values

4.5 Anonymous Go Functions

4.5.1 Declaring an Anonymous Function

4.5.2 Immediate Invocation of Anonymous Functions

4.5.3 Immediate Invocation of Anonymous Functions with Arguments

4.5.4 Assigning Anonymous Function to a Variable

4.5.5 Passing Anonymous Functions as Arguments

4.5.6 Variadic Functions in Golang

4.6 Methods in Go Programming

4.6.1 Receiver Types

4.6.2 Method with User Defined Data Types Other than Structs

4.7 Interfaces in Go

4.7.1 Interfaces with Ordinary Data Types

4.7.2 Type Assertions for Interface

Problems

Chapter-5

Go Structures

5.1 Structures

5.2 Structure Declaration Using the new Keyword

5.4 Types of Structs in Go

5.4.1 Named Structs

5.4.2 Anonymous Structs

5.4.3 Anonymous Fields in a Struct

5.6 Comparing and Assigning Struct Variables

Chapter-6

Go Loops

6.1 For-Loop

6.1.1 The Infinite for-loop

6.1.2 Go Range

6.1.3 The Conditional for-loop

6.1.4 The for-loop with Map

6.1.5 The Nested-for loop

6.1.6 The Continue Statement

6.1.7 Strings with For-Loop

6.1.8 The Break Statement in For-Loop

6.1.9 Do-While Loop Implementation with For-Loop

6.1.10 Goto Statement in For-Loop

6.1.11 For Channel

Problems

Chapter-7

Arrays in Go

7.1 Arrays

7.1.1 Syntaxes for Array Declaration

7.2 Accessing Array Elements

7.3 Array Initialization

7.4 Initialization of Specific Array Elements

7.5 Length of an Array

7.6 Multi-Dimensional Arrays

7.7 Copying Arrays

7.8 Passing Arrays to Functions

Problems

Chapter-8

Slices in Go

8.1 Slices

8.1.1 Zero Valued Slices

8.1.2 Length and Capacity Explanations

8.1.3 Appending Slices

8.1.4 Concatenating the Slices

8.1.5 Removing Elements from a Slice

Problems

Chapter-9

Maps in Go

9.1 Maps

9.1.1 Key Data Type

9.1.2 How to Check Whether a Key Exists or Not?

9.1.3 Map Creation Using make() Function

9.1.4 Nil Map

9.1.5 Removing an Element from a Map

9.1.6 Map Variables

9.1.7 Accessing the Elements of a Map Using For-Loop

Problems

Chapter-10

Pointers in Go

10.1 Introduction

10.2 Address Operator

10.3 Pointer Arithmetic in Go

10.4 Pointer Pointing Another Pointer

10.5 Pointers in Function Arguments

10.6 Functions Returning Pointers

10.7 Function Pointers

10.8 Array of Pointers

10.9 Pointer to a Struct

10.10 Creating Pointers by the New Function

10.11 Make Function for Memory Allocation

Problems

Chapter-11

Concurrency in Go

11.1 Go Routines

11.2 Wait for all Go-Routines to Finish

11.3 Go Channels

11.3.1 Buffered Channel in Go

11.3.2 Using a Loop with a Channel

11.3.3 Range and Close

11.4 Select Statement in Go

11.5.1 Race Condition for Go-Routines

11.5.2 Atomic Operations in Golang

Problems

Chapter-12

File Operations in Go

12.1 File Functions

12.2 Empty File Creation

12.3 Check if a File Exists in Go

12.4 Deleting a File in Go

12.5 Getting File Info

12.6 Opening Files

12.6.1 Open() Function

12.6.2 OpenFile()Function

12.7 Writing to File

12.7.1 Conventional Approach Using the os Package

12.7.2 File Writing Using the ioutil Package

12.7.3 File Writing Using the io Package

12.7.4 Buffered File Writing

12.7.4 Writing Binary Data to a File

12.8 File Reading

12.8.1 Reading All the File Using the ioutil Package

12.8.2 Read File by Chunks

12.8.3 Reading Binary File

Bibliography

Index

About the Author

Chapter-1

Data Types in Go Language

Abstract: In this chapter, we explain the data types used in Go programming. We use built-in functions Printf() and Println() to display the values to the screen. Go is a case sensitive programming language, and it has automatic garbage collector. Unused variables in go programming are not allowed even if they are used for illustrative purposes.

1.1 How to Write a Go Program

Every go program has a main function. For this reason, we first write the structure of the main function as in Code-1.1.

––––––––

Code 1.1

func main(){

}

Inside the main() function, we can write go statements. We write a statement to display the Hello World! sentence to the screen as in Code-1.2.

––––––––

Code 1.2

func main(){

fmt.Println(Hello World!)

}

––––––––

The Println() function used in Code-1.2 is defined in the package fmt, we include this package using import keyword as in Code-1.3.

Code 1.3

import fmt

func main(){

fmt.Println(Hello World!)

}

Finally, we import a special package called main which contains the code that can be built into an executable application, and we get the final form of the program as in Code-1.4.

Code 1.4

package main

import fmt